Gate-controlled amplifiable ultraviolet AlGaN/GaN high-electron-mobility phototransistor.

Area of Science:

• Semiconductor Physics
• Optoelectronics
• Materials Science

Background:

• AlGaN/GaN high-electron-mobility transistors (HEMTs) are crucial for optoelectronic applications.
• The performance of HEMTs is influenced by the AlGaN barrier thickness and gate bias.
• Understanding the interplay between barrier thickness, 2-DEG, and photocurrent is essential for device optimization.

Purpose of the Study:

• To investigate the effect of AlGaN barrier thickness on the performance of AlGaN/GaN HEMT-based phototransistors.
• To demonstrate gate-controlled amplification and attenuation of ultraviolet photocurrent.
• To explore the relationship between gate bias, 2-DEG, and photogenerated carriers.

Main Methods:

• Fabrication of AlGaN/GaN HEMTs with varying AlGaN barrier thicknesses (10 nm and 30 nm).
• Measurement of source-drain dark current and photocurrent under ultraviolet illumination.
• Application of varying gate biases (-1.0 V to +1.0 V) to study gate control effects.

Main Results:

• Dark current increased with AlGaN barrier thickness due to higher piezoelectric polarization-induced 2-DEG.
• Photocurrent decreased with increasing AlGaN barrier thickness.
• Thin AlGaN barriers (10 nm) allowed for gate bias-controlled amplification of photocurrent, while thicker barriers (30 nm) showed no significant gate modulation.

Conclusions:

• AlGaN barrier thickness significantly impacts both dark current and photocurrent in AlGaN/GaN HEMT phototransistors.
• Thin AlGaN barriers are key for achieving gate-controlled photocurrent amplification/attenuation.
• Gate bias offers a powerful tool for tuning the optoelectronic response of these devices.